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A New Proposal 

for 

OSF/UN*X Capabilities 

on PRISM 



Digital Equipment Corporation 
Confidential and Proprietary 



David N. Cutler 

DECwest Engineering 

June 10, 1988 



INTERNAL USE ONLY 



From: 

To: 

Subj: 

From: 
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Subj: 



TLE--KISWA::HEINEN UO-May-1988 1205" 10-MAY-1988 12:04 
MCGREGOR^StAr: : CARDOZA , TLE : : GROVE , NYLANDER 
FYI - more from Supnik on Prism 

urro u/rn OQ-Mav-1988 2217" 9-MAY-1988 22: 

Prism Q & A 



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To: 



cc: 



Ken Olsen 
jack Smith 
Bob Palmer 
Bill Strecker 
Dave Cutler 
Prism Team 
STF 



INTEROFFICE MEMORANDUM 



Date: 9-May-88 

From: Bob Supnik 

Dept : SEG/AFL 

Ext: 225-4947 

Loc: HL02-3/C11 

Enet: ROCK:: SUPNIK 



Subj: 
This 



DEC'S RISC Program: Questions and Answers 
memo answers the following questions about DEC'S RISC program: 

1. [From Ken Olsen] Why are RISC chips faster than VAX chips? 
Summary: Faster cycle time, fewer cycles per function, fewer 
interlocks. 

2. [From Bill Strecker] What i* -quired for • DEC Proprietary RISC 
program to be competitive with the best? 

Summary: Increased investment, in chips, software, systems. 

3. [From Bill Strecker] What are the implications of a proprietary 
RISC program? 

4. [From Bill Strecker] What are the implications of a buyout RISC 
program? 

Summary: More leverage of semiconductor industry, faster time to 
market for first product. 

5. [From Ken Olsen, Bill Strecker] Are we doing everything possible 
for our VAX program? 

Summary: Several higher risk CMOS alternatives could be 
investigated. 
6 [From Jack Smith] What would be the impact of an interim (point) 
MlPS-based workstation product? 



Summary: Short term confusion, long term support costs, low 
product acceptance. 

Details follow. I have appended Dave Cutler's analysis at the end of the 
document . 



DEC'S RISC Program: Questions and Answers 
*** FOR INTERNAL USE ONLY *** 



Page 2 
9 May 1988 



1 WHY RISC? 

[From Ken Olsen: "The Executive Committee has expressed some confusion 
over what can be gained in useful speed with RISC and UNIX as compared to 
VMS. I would appreciate it if you could tell us, some time during the May 
WOODS meeting, what are the limitations on speed for VAX chips as compared 
to UNIX [RISC] chips."] 

Using equal technology, RISC chips outperform VAX chips for the following 
reasons: 



1. 



3. 



Shorter cycle time. VAX chips have more, and longer, critical 
paths than RISC chips. The worst VAX paths are the control store 
loop and the variable length instruction decode loop, both of 
which are absent in RISC chips. 

Fewer cycles per function. Although VAX chips require fewer 
instructions than RISC chips (1:2.3) to implement a given 
function, VAX instructions take so many more cycles than RISC 
instructions (5-10:1-1.5) that VAX chips require many more cycles 
per function than RISC chips. 

Increased pipelining. VAX chips have more inter- and 
intra-instruction dependencies, architectural irregularities, 
instruction formats, address modes, and ordering requirements 
than RISC chips. This makes VAX chips harder and more 
complicated to pipeline. 

Lower transistor count. VAX chips require more transistors and 
are thus harder to map into lower density but higher performance 
technology. 



In VLSI CMOS technology, RISC delivers 3X the raw performance 
(All numbers reflect performance at WORST CASE parameters.) 



of VAX. 



Technology 

2u CMOS 
1.5u CMOS 
l.Ou CMOS 
.75u CMOS 



RISC 



vups 



VAX 



vups 



R2000 10 


CVAX 


3 


Prism >20 


Rigel 


6 


Prism-3 >30 


Mariah 


10 


Prism-4 >60 


NVAX 


20 



2 A COMPETITIVE RISC PROGRAM 

A fully competitive RISC plan would include chips, technology, software, 
and sources. 



2.1 Chips 

Chip Technology 



Vups 



DEC plan 



DEC'S RISC Program: Questions and Answers 
*** FOR INTERNAL USE ONLY *** 



Page 3 
9 May 1988 



Samples 



1987 


CMOS 


1988 


CMOS 


1989 


CMOS 


1990 


CMOS 


1991 


CMOS 


1989 


ECL 


1990 


ECL 


1991 


ECL 



Actions required: 



10 
20 
30 
40 
60 

40 
80 
120 



uPRISM @ 25ns - >20 vups 
uPRISM @ 18ns - >30 vups 
uPRISM-3 @ 13ns = >40 vups 
uPRISM-4 = >60 vups 

? \possible: chilled air uPrism\ 
? \possible: chilled CMOS uPrism\ 
? \possible: first ECL uPrism\ 



1. An extra MOS design team is needed, so that shrinks and 
variations of the existing uPRISM design can be explored while 
Cheela is being built. 

2. A schedule and performance target for an ECL Prism must be 
selected asap, and a project started. 

3. Gaps at the high end must be filled with cooled (or chilled) CMOS 
until an ECL chip set is ready. 



2 . 2 Technology 

Chip Technology 
Samples 



1987 
1988 
1989 
1991 

1989 
1991 



2.0u CMOS 
1.5u CMOS 
l.Ou CMOS 
.75u CMOS 



(DEC uses drawn poly, industry uses effective poly.) 



(by industry reckoning: 1.2u) 

(by industry reckoning: l.Ou) 

(by industry reckoning: 0.7u) 

(by industry reckoning: 0.55u) 



MCA-3 equivalent custom ECL 
MCA-4 equivalent custom ECL 



2.3 Software 

The key software requirements are: 

- Compilers. Optimizing, uPrism-focussed compilers with efficient 
calling standard (low overhead, optional debug hooks) and link 
time register allocation. 

- Operating System. Streamlined O/S with high performance Unix, 
VMS system service interfaces, low latency I/O, and high 
reliability. 



DEC'S RISC program: Questions and Answers Pa ?o ft o 

*** PflB INTERNAL USE ONLY *** y na Y iyoa 



2.4 Sourcing 



A proprietary architecture does not imply that all design and/or all 
manufacturing is done internally. In CMOS, SCO is looking for outside 
foundries that can provide a time to market and/or performance advantage 
over internal processes. In ECL, DEC should look for both outside 
foundries and outside design help. If desired, DEC can leverage access to 
the Prism architecture to form partnerships with outside resources. 



3 IMPLICATIONS OF PRISM STRATEGY 
Advantages: 

- Architectural control, on issues like transition to 64b. 

- Business control for non-Unix-based products. 

- VAX compatability where it counts -- data types, vector model, 
interlocks, I/O models, etc. 

- Guaranteed binary compatability across generations. 

- Tight linkage to software on 0/S, mP, and reliability issues. 

- Guaranteed linkage to emerging security models. 

- Capability for cryogenic (77k) operation. 

Disadvantages: 

- Lack of access to industry design resources (particularly ECL), 
technology, and foundries. 

- Larger internal investment in processor development. 

- Slower time to market with first RISC product. 



4 IMPLICATIONS OF BUYOUT STRATEGY 
Implications: 

- DEC customer base, both Unix and proprietary users, is open to 

clones. 

- Cartel/partnership arrangements mandatory for base processor 
designs, including strong measure of architectural and 
implementation control. 

- Buyout orientation for (Unix based) software. This may lead to 
interoperability problems (eg, language interoperability). 

Advantages: 

- Leverages semiconductor industry design, technology, 
manufacturing base. 

- Reduces internal investment in processor development. 

- Faster time to market with first RISC product. 

Disadvantages: 



DEC'S RISC Program: Questions and Answers Pa ?ooo 

*** FOR INTERNAL USE ONLY *** » Ma 7 1988 

- Lack of full architectural control, with risks on vectors, 
multiprocessors, generation to generation compatability. 

- High probability of destabilizing non-Unix portions of Prism 
program. 

- High probability of destabilizing any internal implementation of 
RISC architecture. 

- Vulnerable to forward integration by suppliers. 

- As VAX business declines, foreshadows end of DEC'S processor 
business. 

- Incompatible with cryogenic (77k) operation. 



5 DEC'S VAX BUSINESS 

[From Ken Olsen: "If VAX is the heart of our business and it is the 
proprietary part of our product line, are we putting enough resources into 
it?" From Bill Strecker; "What is the opportunity cost of Prism?"] 

HPS is working on high risk ECL based VAX's, and SEG on somewhat lower 
risk VLSI based VAX's. An additional effort could be mounted to look at 
the fastest possible VMS engine in VLSI. Possibilities: 

1. «The fastest possible conventional VAX (further tpi reductions, 

tighter cycle times, probably traded against schedule). There is 
little to be achieved here, I believe, beyond NVAX and Centaurus. 

2. Porting VMS to a faster (RISC) architecture. This was estimated 
at 2.5 years in 1984 and would probably take longer today. 

3. "RlSCy VAX" (subsetted instructions and address modes, extended 
virtual address) and revised software, aiming at "EVAX/EVMS", 
with better RISC: VAX performance ratio. Problem: If not binary 
compatible and requires substantial revisions to VMS and customer 
software, why is this better than Prism? 

The resources devoted to Prism are orthogonal to such an effort. To date, 
Prism has tended to spur the VAX hardware and software groups to greater 
functionality and performance in their projects. 



6 AN INTERIM UNIX WORKSTATION 

[From Jack Smith: What would be the impact of an interim (point) Unix 
workstation based on the R2000 chip?] 

A temporizing strategy, starting with industry chips and switching to 
Prism, is worse than either a pure buyout strategy or a pure proprietary 
strategy, for the following reasons: 



DEC'S RISC Program: Questions and Answers Page 6 

*** FOR INTERNAL USE ONLY *** 9 May 1988 

1. User perceivable incompatabilities. The interim workstation 
would use MIPS compilers, the Prism workstations, DEC compilers. 
There would be visible differences in the languages. 

2. Application rework required. Because of the switchover, ISV's 
would have to port their applications a second time to the Prism 
products. 

3. Ongoing support burden. Since the interim workstation would 
require long term support, DEC would be supporting THREE versions 
of Unix (VAX, MIPS, Prism) and the Unix compilers. 

4. Poor market acceptance. Point products, particularly point 
desktop products, have done poorly in the marketplace. Customers 
will ask, at the outset, what the followon product is and are 
unlikely to be satisfied with a switchover solution. 

5. Division of internal focus. The interim product would create a 
permanent internal lobby for followon products, thereby 
increasing intergroup squabbling and decreasing productive work. 



DEC'S RISC Program: Questions and Answers Page 7 

*** FOR INTERNAL USE ONLY *** 9 May 1988 

Appendix: Dave Cutler's Responses to Selected Questions 

From: DECWET :: CUTLER 6-MAY-1988 19:29 

To: ROCK::SUPNIK 

Sub j : As promised my input - I hope this helps. 

1. What would constitute a RISC program that is competitive against the 
best of the industry (eg, MIPSCo or Spectrum or SPARC)? in terms of 

- processors 

- software 

- sourcing and partnerships 

That is, in terms of what an industry RISC buyout would provide? 
The answer must cover both MOS and ECL implementations. 

> 

>I think the current program using PRISM is the only way to get a 
>long-term competitive RISC program. But do to that we have to have 
>more funding behind it. The amount of funding going into the PRISM 
>program today is not sufficient. 
> 

2. What are the concrete advantages, to DEC, of a proprietary RISC 
architecture? This is not a question of why Prism is better than 
other RISC machines, although that is certainly interesting data. 
Rather, the question is what competitive advantages does DEC derive 
in the Unix and non-Unix marketplaces from a "vanity" (other peoples' 
word) RISC ISP? 

>The first, and most obvious, advantage to Digital of a proprietary architecture 
>is that its let's us address the question of compatibility with our existing 
>customer base in the most optimal way. Most RISC vendors have designed their 
architectures with no regard to any customer base and have thus optimized the 
architecture for the current circuit technology. A Digital based design would 
>want to take into account our large customer base and be in a strong position 
>to migrate our customers to the new architecture. This was in fact a strong 
>design goal for PRISM. Examples are memory addressing, interlocks for I/O 
controller compatibility, and floating point format. 

>The second most obvious advantage to Digital is that it let's us control our 
>destiny. The current RISC vendors typically work closely with their suppliers 
>to produce implementations of their architectures in new technologies. These 
> implementations are not available to the public until they have been fully 
>developed and integrated into their respective company's product line. This 
>puts Digital at a competitive disadvantage. Another aspect of this that is 
>would put us at the mercy of the another vendor with respect to compatibility 
>o£ each generation of chips with the next. 

>Some of the semiconductor houses themselves produce RISC architecture chips 
>and certainly make them available to everyone immediately. But the fact that 
>they are available to everyone equally does not give Digital any advantage 
>in an area where we have enjoyed an advantage in the past. 

>Most, if not all, RISC architectures offered by competitors have taken very 



DEC'S RISC Program: Questions and Answers Fage 8 

*** FOR INTERNAL USE ONLY *** 9 May 1988 

>little into account with respect to evolving circuit technology. They have 
>been optimized for the current technology. This will eventually force changes! 
>in these architectures that will be incompatible. A good example of this is 
>the lack of integration of floating point into the instruction set, the use 
>of condition codes, and the lack of vector architectures. None of the RISC 
architectures offered by competitors will allow an easy migration to larger 
>address spaces. In general, most RISC architectures optimize the integer 
instruction set and make everything else a bag on the side. PRISM on the 
>other hand has taken into account future technology and will allow us to 
>gain more performance without incompatible changes to the architecture. 

>PRISM has also been designed with the ultimate goal of migrating to a 64-bit 
architecture. No other RISC architecture has been designed with this goal. 
>This is the single biggest reason for going from one architecture to another. 
>With an upward compatible 64-bit architecture in its back pocket, Digital is 
>assured of a very lengthy life for the PRISM architecture. This cannot be 
>said of other vendors. 

>The question here really, is whether Digital can do better than the competition 
>with respect to architecture design. I think we have unquestionly proved that 
>with the VAX architecture. If Digital can no longer be a leader in the design 
>of computer and software architectures, then we are destined to become a me 
>too vendor. 

Specifying our own architecture allows us to optimize our software around 
>that architecture. Using industry standard parts will probably force us to 
>compete at the lowest common denominator. In other words we will be forced 
>to design software that takes advantage of very little but the instruction 
>set of the host architecture. 

>The PRISM architecture allows us to migrate to 64-bits in the future with 
>little impact on the customer base. This cannot be said of any other RISC 
>vendor. This allows us to decide when we want to do it, to do it compatibly, 
>and to lead the market when we do it. 

>So I think the question here is more than a "vanity" Digital proprietary 
architecture. I think the question goes to the heart of Digital being able 
>to design and build systems with competitive price performance that allow 
>maximum attainable compatibility with our current systems. We will not get 
>this using industry RISC chips. 
> 

3. What are the advantages and implications of going over to RISC buyout 
technology? Leaving aside the details of "Plan B", what would benefits 
would accrue to DEC if it bought out its RISC engines? 

>There are two advantages that I could see exposed: 1) we get better and 
>more competitive chips because they are produced by more semiconductor 
>houses, 2) we can get products into the market faster with industry standard 
>chips. 

>ln the past, standard chips have also fostered the development of support 
>chips that all plug together. This would cut down on the number of designs 



DEC'S RISC Program: Questions and Answers Page 9 

*■** FOR INTERNAL USE ONLY *** 9 Ma Y 1988 

>that must be done for a new system and could make time to market faster. 
>Contrary to this argument, however, is that support chips are not as 
>important as they once were in discrete designs. Technology is moving us 
>more and more toward total systems practically on a single chip. So this 
>may not be a real advantage. 

>0n the other hand, we could use more semiconductor houses ourselves with 
>our own architecture if that became necessary. A negative side to using 
>industry chips is that everyone has equal access to the chips (the vendor 
>itself has better accessl). This means that one degree of freedom has been 
>taken away from us with respect to adding value. 

>The second advantage of getting systems into the market faster is questionable. 
>New proposals always are cheaper, faster, earlier, and cost less to produce. 
>Very few ever achieve all these goals. I seriously question whether using 
>industry standard chisp let's us get a product into the market that has a 
competitive advantage. 

>Certainly the implications of using industry chips are far reaching. If we 
>decide to use industry standard chips we will have to abandon the PRISM effort. 
>We simply will not be able to get enough resources to support VAX, PRISM, and 
>another architecture. What does this mean? I think it means that Digital will 
>be forced to relinquish all hope of ever adding value in the hardware space 
>and will have to instantaneously change its profit model from hardware to 
>software and support - something that probably cannot be adequately managed 
>in a short timeframe. We will have to add all of our value in software and 
>service. The VAX architecture will sustain our growth for a short few years 
>and then we'll be just another vendor. Perhaps we could even change our company 
>name to Dunisys (pronounced Done-i-sys). 
> 

4. What is the "opportunity cost" of Prism? What could be done in the VAX 
space (hardware and software) that is not being done because of the 
allocation of resources and innovation to Prism? (Ken also asked this 
question. ) 

>The single, I say single, most important thing the PRISM architecture has 
>done to date is get the VAX system designers and architects to make VAX 
>more competitive. The addition of vectors to the VAX architecture came as 
>an outgrowth of the PRISM architecture having them. The addition of SMP to 
>VMS came as an outgrowth to the PRISM operating system supporting it. The 
> recent emphasis on the Common Multithreading Architecture is because of the 
>PRISM operating system. The performance of the current generation of high 
>end VAXes was originally 15-20x780 for Aquarius and 10-12x780 for Argonaut. 
>When the performance goals of the orginally proposed PRISM products was 
>made public, suddenly the VAX implementers realized that they had not set 
>their goals high enough. In fact, I was in a meeting at Jack Smith's staff 
>in 1986 when the performance of Aquarius rose to 30x780 on the spot! 

>So I could turn this around and say what would be lost if the effort on 
>PRISM were stopped. 

>I can't think of a single thing that we could do with the resources that 



DEC'S RISC Program: Questions and Answers Pa9 ? £2 

*** FOR INTERNAL USE ONLY *** 9 May 1988 

>are working on PRISM that could help us in the VAX space. We certainly 
>have enough VAX processors under development. Maybe we could get them 
>faster or with more features if we had more people to work on them. They 
>still wouldn't be more competitive, however. I think that Brook's law 
>would prevail and this would actually cause the products to appear later. 
>We are already spending heavily in the VMS and ULTRIX software areas. 
>Perhaps additional capabilities or layered products could be developed. 

>I think a very pertinent question is how much more could we get out of 
>the PRISM strategy if we weren't spending so heavily in the VAX area. 
>Maybe this is the time to bring up the cancellation of either Argonaut 
>or Aquarius. 

>One thing we could do is get a custom bipolar chip set started earlier 
>for PRISM, or alternatively be more aggressive with our next CMOS 
>PRISM chip set. These just might be more important questions to ask. 

>Asking this question is a mute point in reality anyway. The fact of the 
>matter is that if the PRISM work is stopped everything will come to a 
>screeching halt for 6-12 months. This is a cold hard fact. I know that 
>upper management doesn't like to listen to these kinds of arguments. 
>But that doesn't make them any less real. We would have been to market 
>earlier with the current products if the strategy hadn't gotten jerked 
>around so much over the last 3 years. Jerking it again won't produce 
>any benefits for the VAX line. 
> 

I would very much value your inputs. 
/Bob 

>This is last because it is on a philosophical note. I couldn't resist 
>the temptation of including it. 

>This whole discussion brings up the question of "ownership" and corporate 
> "pride". 

>When people are allowed to build on their own ideas they develop a strong 
>sense of ownership and pride in their work - they strive hard to make it 
>the best and to be better than everyone else. 

>When people are told what to do using someone else's ideas they do not 
>develop any sense of ownership or pride - it is somebody's else's idea, 
>it is somebody else's problem if it doesn't work, and it is somebody 
>else's problem if it isn't on time. 

>The best products built at Digital were built by groups that had strong 
>ownership and pride in their product. 

>The same argument can be applied to Digital as a whole - we sell, market, 
>engineer, and support products best that are ours. A good example of bad 
>support is ULTRIX. If you ask a Digital salesman what he'd rather sell 
>VMS or ULTRIX he'll say VMS - it is OUR product. 



DEC'S RISC Program: Questions and Answers Page 11 

*** FOR INTERNAL USE ONLY *** 9 May 1988 

> 

>Adopting a nonDigital architecture is paramount to admitting technical 
>and competitive defeat. Whereas now this might only effect the workstation 
>space it will ultimately effect the entire VAX product line because of 
>VAXes inherent complexity and inability to keep stride with industry 
>price and performance. 
> 



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